A spokeswoman for Duesseldorf police Anja Kynast said the man arrested was also injured.
Attackers wielding axes injured five people at the main train station in the west German city of Duesseldorf late Thursday, local police told AFP.
Another police spokesman, Andreas Czogalla, said that at least one of the victims had been seriously injured, and that there were no indications of other attackers.
"I helped her wound and called her father", she said.
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Anti-terror police sealed off the German city's main train station when the attack happened at around 9pm local time (8pm United Kingdom time).
Regional police posted on Twitter saying that a "comprehensive" police response was underway and that the train station was closed. The rail station remained shut down, he added. "The whole station is full of police officers".
The train station has been sealed off and trains have been diverted from the station while police deal with the incident.